1. Quorum Sensing
This whole field has been created by Dr. Bonnie Bassler. She happened to hear a lecture in which a professor proposed the idea that bacteria were somehow communicating, and she tracked him down, asked to work in his lab, and then proceeded to figure out how bacteria communicate. She essentially created an entirely new field of microbiology – and her work is paving the way for new antibiotics. Future nobel prize winner???

2. Model Organism
Lux operon

3. The basic mechanics autoinducers
 enable populations of bacteria to coordinate regulation of gene expression and behavior, on a community-wide scale

4. Autoinducers synthesized intracellularly.
either passively released or actively secreted outside of the cells.
number of cells increases = extracellular concentration of autoinducer increases.
minimal threshold level required for detection
Once threshold is hit, receptors bind the autoinducers and trigger signal transduction cascades that result in population-wide changes in gene expression.

5. These are the three protein receptors involved in detecting autoinducers for quorum sensing

6. gene regulation Low level, kinase model of cell communication
LuxO = regulator protein
Product degrades mRNA that stimulates group behavior
High level – switch to phosphatases, LuxO activity shuts down, mRNA that stimulates group behavior is left intact  bioluminesce
After reading several of Dr. Bassler’s papers, this is what I have been able to glean.

8. End Product
enables population of cells to function in unison = collective behavior
Achieve multicellularity – acting as one unit

9. Example: Virulence factor expression
 molecules produced by pathogens and contribute to the pathogenicity of the organism
Help to colonize niche in host, evade or inhibit immune system of host, get energy from host, and get into/out of host cells

10. Example: Formation of biofilms
group of microorganisms in which cells stick to each other on a surface
Have different phenotypic properties than “free-dwellers” of same species
Embedded within self-produced matrix – slime
Increased resistance to detergents and antibiotics
Dental plaque is a perfect example

11.
One of my primary resources for building this powerpoint.

12. In case you are interested in finding out more about this woman’s work, and her life story.